Polymer nanoparticles and nanofibers: Drug delivery and environmental applications

Since \u201cnanotechnology\u201d was presented by Nobel laureate Richard P. Feynman during his well famous 1959 lecture \u201cThere\u2019s Plenty of Room at the Bottom\u201d, there have been made various revolutionary developments in the field of nanotechnology. However, nanotechnology has emerged in the last decade as an exciting new research field. Nanotechnology represents the design, production, and application of materials at atomic, molecular and macromolecular scales, in order to produce new nanosized structures where at least one dimension is of roughly 1 to 100 nm, i.e., less than 0.1 \u3bcm. However, materials below or next to 1 \u3bcm (1000 nm) can be also commonly referred as nanomaterials or, more correctly, ultrathin materials. According to this, specifically within fiber science related literature, fibers with diameters below 1 \u3bcm are broadly accepted as nanofibers. Nanotechnology and nanoscience studies have emerged rapidly during the past years in a broad range of product domains. Today, nanoscience represents one of the rapidly growing scientific disciplines due to its enormous potential and impact in many different technological and engineering applications, which includes the development of new materials with novel and advanced performances. Recently, the nano-scaled materials have attracted extensive research interests due to their high anisotropy and huge specific surface area. Furthermore, the continuously increasing interest in the nanostructure materials results from their numerous potential applications in various areas, particularly in biomedical sciences. Today, nanofibers and nanoparticles are at the forefront of nanotechnology because of their unique properties such as low density, extremely high surface area to volume ratio, flexibility in surface functionalities, superior mechanical performance (e.g. stiffness and tensile strength), and high pore volume and controllable pore size that cannot be found in other structures. In this context, our researches have been concentrated on the production and modification of polymeric nanofibers and nanoparticles as drug delivery and environment applications. To this purpose, selected materials for the nanofibers development (polyhedral oligomeric silsesquioxanes, modified poly(amido-amine) dendrimers, and modified hyperbranched polyglycerol) were combined with biopolymers, namely (poly(L-lactide) (PLLA) and poly(\u3b5-caprolactone) (PCL) which enable us to overcome typical shortcomings of the above polymer matrices. As well, poly(styrene-co-maleic anhydride) (PSMA) amphiphilic copolymer was used for production of nanoparticles

Star poly(ε-caprolactone)-based electrospun fibers as biocompatible scaffold for doxorubicin with prolonged drug release activity

Abstract In this work, a novel drug delivery system consisting of poly(e-caprolactone) (PCL) electrospun fibers containing an ad-hoc-synthesized star polymer made up of a poly(amido-amine) (PAMAM) core and PCL branches (PAMAM-PCL) was developed. The latter system which was synthesized via the ring opening polymerization of e-caprolactone, starting from a hydroxyl-terminated PAMAM dendrimer and characterized by means of 1H NMR, IR and DSC, was found to be compatible with both the polymer matrix and a hydrophilic chemotherapeutic drug, doxorubicin (DOXO), the model drug used in this work. The preparation of the dendritic PCL star product with an average arm length of 2000 g/mol was characterized using IR and 1H NMR measurements. The prepared star polymer possessed a higher crystallinity and a lower melting temperature than that of the used linear PCL. Electrospun fibers were prepared starting from solutions containing the neat PCL as well as the PCL/PAMAM-PCL mixture. Electrospinning conditions were optimized in order to obtain defect free fibers, which was proven by the structural FE-SEM study. PAMAM moieties enhanced the hydrophilicity of the fibers, as proved by comparing the water absorption for the PCL/PAMAM-PCL fibers to that neat PCL fibers. The drug-loaded system PCL/PAMAM-PCL was prepared by directly introducing DOXO into the electrospinning solutions. The DOXO-loaded PCL/PAMAM-PCL showed a prolonged release of the drug with respect to the DOXO-loaded PCL fibers and elicited effective controlled toxicity over A431 epidermoid carcinoma, HeLa cervical cancer cells and drug resistant MCF-7 breast cancer cells. On the contrary, the drug-free PCL/PAMAM-PCL scaffold demonstrated no toxic effects on human dermal fibroblasts, suggesting the biocompatibility of the proposed system which can be used in cellular scaffold applications

Recent Advances in the Development of Biomimetic Materials

: In this review, we focused on recent efforts in the design and development of materials with biomimetic properties. Innovative methods promise to emulate cell microenvironments and tissue functions, but many aspects regarding cellular communication, motility, and responsiveness remain to be explained. We photographed the state-of-the-art advancements in biomimetics, and discussed the complexity of a "bottom-up" artificial construction of living systems, with particular highlights on hydrogels, collagen-based composites, surface modifications, and three-dimensional (3D) bioprinting applications. Fast-paced 3D printing and artificial intelligence, nevertheless, collide with reality: How difficult can it be to build reproducible biomimetic materials at a real scale in line with the complexity of living systems? Nowadays, science is in urgent need of bioengineering technologies for the practical use of bioinspired and biomimetics for medicine and clinics

Hyperbranched PDLA-polyglicerol: A novel additive for tuning PLLA electrospun fiber degradation and properties

In this paper, it was developed the synthesis of a novel polymer additive potentially capable of modifying the features of electrospun fibers based on poly(L-lactide) (PLLA). Indeed, the above molecule, which was designed by taking into account both the features of the polymer matrix and the specific applications of the final material, was made up of a high-molecular-mass hyperbranched polyglicerol (HBPG) core and poly(D-lactide) (PDLA) arms (HBPG-PDLA). 1H NMR characterization allowed to assess the successful preparation of the dendritic HBPG-PDLA, synthesized by means of ring opening polymerization (ROP) of D-lactide, as well as the number average molecular weight per arm, that is about 1100 g/mol. Moreover, by combining 1H NMR and TGA results, it was determined an average number of polylactide arms of about 300. Electrospun fibers based on PLLA and HBPG-PDLA were prepared by directly adding the as-synthesized dendritic additive into the electrospinning solution to a final concentration of ca. 25 wt.%. FE-SEM analysis of the system, prepared by applying the optimized electrospinning conditions, demonstrated the formation of defect-free fibers without separated, micrometric domains of the additive. The thermal properties of both neat PLLA and composite fibers were studied by DSC analysis. The partial stereocomplexation of the systems containing HBPG-PDLA, resulting from the combination of the PDLA arms of the dendritic polymer with the chains of PLLA, was confirmed by calorimetric measurements as well as by X-ray diffraction analysis. The dendritic additive, featuring the hyperbranched polyglycerol core, was found to enhance the hydrophilicity of the fibers and consequently their enzymatic degradation rate, which turned out to be much higher than that of the neat PLLA fibers. Unlike the organic additives usually applied to modify the properties of PLLA, the addition of HBPG-PDLA to the fibers was also found to lead to an increase of the mechanical properties of the composite systems, that is an increment of their Young's modulus

Poly(styrene-co-maleic anhydride) nanoparticles as protein carriers

Considering the increasing interest for protein immobilization on nanoparticles, in this work, we demonstrate the preparation of poly(styrene-co-maleic anhydride) (PSMA) nanoparticles and their capability to conjugate the proteolytic enzyme papain. PSMA nanoparticles were fabricated by combining precipitation and electrospray technique. Different experimental conditions were tested in order to optimize nanoparticle dimensions and production yield and different techniques were used to characterize the produced nanoparticles. Their mean diameter was found to be 176 nm. The successful papain-nanoparticle conjugation was then demonstrated. The residual catalytic activity of the conjugated enzyme was studied and found to be around 79% respect to the free enzyme

Biobased System Composed of Electrospun sc-PLA/POSS/Cyclodextrin Fibers To Remove Water Pollutants

In this work, a novel biobased system, characterized by specific features suitable for the removal of water pollutants, was developed. Indeed, the system consists of electrospun stereocomplex polylactide (sc-PLA)-based fibers, prepared from solutions containing equimolar amounts of high-molecular-weight poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA), functionalized with an amino polyhedral oligomeric silsesquioxanes (POSS-NH2), which was added directly into the electrospinning solution. The sc-PLA/POSS-NH2 fibers, characterized by a submicrometric dispersion of the silsesquioxanes, underwent a grafting reaction with \u3b2-cyclodextrin molecules, activated to nucleophilic substitution via monotosylation (CD-O-Ts). The reaction was first investigated on neat POSS-NH2 and optimized conditions were then applied for sc-PLA/POSS-NH2 fibers. Indeed, IR and XPS measurements demonstrated the formation of a novel hybrid molecule, characterized by the linkage of the cyclodextrin to the silsesquioxane siliceous cage (POSS-NH-CD). Concerning the fibers, SEM measurements evidenced that the treated mats show a higher surface roughness than the neat ones, whereas by applying TGA analysis it was possible to evaluate the amount of the grafted cyclodextrin, which was found to be 3 wt %, that is a quantity correlated with the concentration of POSS-NH2 in the fibers (5 wt %). Moreover, the surface wettability of the fibers turned out to increase as a consequence of the surface grafting. Finally, UV measurements demonstrated the capacity of the novel synthesized hybrid molecule, based on POSS and cyclodextrin, to absorb water pollutants, by having chosen, as model compounds, alizarin red and 2-chlorophenol. Indeed, it was demonstrated that the grafting of CD on the surface of sc-PLA/POSS-NH2 fibers enhanced the absorption capacity of the system